Season 5 opens with Severide and Stella searching for Grant, who's AWOL from Chicago Med; Dawson questioning her career path; Casey's relationship with his political consultant cooling; and Borrelli's anger at Boden over his brother's death boiling over.

The story of firefighters in Chicago. Following the apartment fire explosion with everyone inside, everyone at Firehouse 51 survives, Mills with a broken leg, but Shay is killed on scene leaving everyone mourning her loss. The episode forwards to six weeks later where we find many in the Firehouse have taken her death hard. Severide, having been on leave after the incident is now AWOL, eventually Casey finds him at his cabin where he admits he';;;s reluctant to return. Also, Casey continues to butt heads with Lieutenant Welch at Truck 66, Boden and his wife double date with Mouch and Trudy.

For the firefighters, rescue squad and paramedics of Chicago Firehouse 51, no occupation is more stressful or dangerous, yet so rewarding and exhilarating. These courageous men and women are among the elite who forge headfirst into danger when everyone else is running the other way and whose actions make the difference between life and death. While Severide finds himself being targeted by a dangerous arsonist, Firehouse 51 takes on new blood and new rules to avoid shuttering its doors due to budget cuts. Casey finds himself with new responsibilities.

The show follows the lives of the firefighters and paramedics working at the Chicago Fire Department at the firehouse of Engine 51, Truck 81, Squad 3, Ambulance 61 and Battalion 25. These courageous men and women are among the elite who forge headfirst into danger when everyone else is running the other way and whose actions make the difference between life and death. The pressure to perform on such a high level has a way of taking a personal toll, sometimes putting team members from the Truck and the specially trained Rescue Squad at odds with each other. Despite any differences, this is an extended family, and when it';;;;s "go time," everyone inside Firehouse 51 knows no other way than to lay it all on the line for each other.